The invention relates to an ink cartridge for inkjet printers, having an outer housing and an ink container located inside, in particular an ink bag, which comprises an ink outlet piece through which the ink container can be contacted from the outside in a fluid-conductive manner.
From U.S. Pat. No. 5,666,146 an ink cartridge for the self-aligning insertion in a printer is known. Said ink cartridge comprises an outer housing, which in practice is produced from plastic, in which an ink bag is provided, the flexible outer walls of which are formed by aluminium or nylon film. The ink bag can be contacted in a fluid-conductive manner from the printer through an ink outlet piece by way of interface means or puncturing means belonging to the printer. To this end, a puncturing needle of the interface means of the printer punctures the ink outlet piece when the ink cartridge is inserted in the printer. On a front wall of the outer housing, guide openings are provided, which serve for receiving guide extensions on the printer side. These guide openings interact with the extensions on the printer side such that when the cartridge is inserted in the printer, the cartridge first contacts the extensions on the printer side and is brought in position through these. Following this, the puncturing needle punctures the ink outlet piece in a defined position. When the cartridge punctures the printer the guiding function of the guide openings is ensured through the extensions on the printer side abutting the inner circumference of the guide openings or through the resultant backpressure. This is achieved in that the diameter of the extensions on the printer approximately corresponds to the diameter of the guide openings. Furthermore, a support plate is provided on the ink bag which serves to stiffen the ink bag on a bag side. On the support plate, a filling level indicator is provided, which as soon as the ink bag is (almost) empty of ink, protrudes through a recess in the outer housing. In this case, the filling level indicator can exert pressure on a switch (attached outside the ink cartridge) in the printer, as a result of which on the printer side a low ink filling level in the cartridge can be detected.
A similar ink cartridge is described in DE 692 14 512 T2 (EP 016 088 B1). The ink cartridge described there is characterized in that the ink outlet piece is designed circular in cross section and in that in the ink outlet piece a circular groove is formed, which is positively connected to the outer housing such that the ink outlet piece is held and positioned in a predetermined position relative to the housing. In the outer housing, a semi-circular notch is provided for receiving the groove of the ink outlet piece.
In U.S. Pat. No. 6,053,606 an ink cartridge is disclosed, in which the support plate comprises portions projecting away in a co-planar manner, through which the support plate supports itself on the outer housing. On emptying the ink cartridge, the portions projecting away in a co-planar manner rub along the inside of the outer housing.
Especially in recent times, more value is attached to an environmentally friendly use of resources. The plastic cartridges of the prior art however can only be disposed in an environmentally friendly manner with much effort. In addition, plastic requires mineral oil, a raw material which is becoming increasingly valuable.
From U.S. Pat. No. 7,488,059 B1 a so-called “bulk ink system” is known, in which an ink reservoir arranged outside the printer supplies an ink cartridge (provided in addition to the ink reservoir) arranged in the printer by means of an ink feed line. The guiding means-free housing of the ink reservoir in this case can be of cardboard or plastic. In contrast with the commercially available plastic ink cartridge, no centring of the freely positionable ink reservoir is necessary.
From DE 44 25 694 A1 a further such “bulk ink system” is also known, wherein the guiding means-free housing of the freely positionable ink reservoir is of cardboard. The ink cartridge which is connected to the ink reservoir via an ink line is a moulding, usually of a half plastic, which is adapted to the shape of the cartridge receiving region of the printer.
From US 2005/0151813 A1 a printing frame, in particular for the printing of T-shirts is known, in which a multiplicity of freely positionable and guiding means-free ink reservoirs are placed onto a frame. The ink reservoirs are connected to the printing head via flexible hoses, which are to ensure that they can be freely positioned.
It is thus altogether known with ink reservoirs, which are connected by way of locally flexible hoses, to also produce the outer housing from a cellulose material such as cardboard or pasteboard. In the cases in which the ink reservoir supplies an ink cartridge positioned in the printer these are commercially available plastic cartridges. In contrast with the previously described freely positionable ink reservoirs provided in addition to the ink cartridges, ink cartridges comprise guiding means in order to align or to centre the ink cartridge relative to the fixed-location puncturing or interface means in the printer when being pushed in. For this purpose, the interface means can comprise counter-guiding means, wherein these guide the ink cartridge into a desired position through a counter-force on the guiding means when the ink cartridge is inserted.